Remote Ischemic Preconditioning and Kidney Injury After Cardiac Surgery | Journal Scan

Study Questions:

What is the effect of remote ischemic preconditioning (RIPC) on the rate and severity of acute kidney injury in patients undergoing cardiac surgery?

Methods:

The RenalRIPC investigators enrolled 240 patients in this multicenter trial, at high risk for acute kidney injury, as identified by a Cleveland Clinic Foundation score of 6 or higher, between August 2013 and June 2014, at four hospitals in Germany. They randomized them to receive RIPC or sham RIPC (control). All patients completed follow-up 30 days after surgery and were analyzed according to the intention-to-treat principle. Patients received either RIPC (3 cycles of 5-minute ischemia and 5-minute reperfusion in one upper arm after induction of anesthesia) or sham RIPC (control), both via blood pressure cuff inflation. The primary endpoint was the rate of acute kidney injury defined by Kidney Disease: Improving Global Outcomes criteria within the first 72 hours after cardiac surgery. Secondary endpoints included use of renal replacement therapy, duration of intensive care unit stay, occurrence of myocardial infarction and stroke, in-hospital and 30-day mortality, and change in acute kidney injury biomarkers.

Results:

Acute kidney injury was significantly reduced with RIPC (45 of 120 patients [37.5%]) compared with control (63 of 120 patients [52.5%]; absolute risk reduction, 15%; 95% confidence interval [CI], 2.56%-27.44%; p = 0.02). Fewer patients receiving RIPC received renal replacement therapy (7 [5.8%] vs. 19 [15.8%]; absolute risk reduction, 10%; 95% CI, 2.25%-17.75%; p = 0.01), and RIPC reduced intensive care unit stay (3 days [interquartile range, 2-5]) vs. 4 days (interquartile range, 2-7) (p = 0.04). There was no significant effect of RIPC on myocardial infarction, stroke, or mortality. RIPC significantly attenuated the release of urinary insulin-like growth factor–binding protein 7 and tissue inhibitor of metalloproteinases 2 after surgery (RIPC, 0.36 vs. control, 0.97 ng/ml2/1000; difference, 0.61; 95% CI, 0.27-0.86; p < 0.001). No adverse events were reported with RIPC.

Conclusions:

The authors concluded that among high-risk patients undergoing cardiac surgery, remote ischemic preconditioning significantly reduced the rate of acute kidney injury and use of renal replacement therapy.

Perspective:

This study reports a 15% absolute reduction in the rate of perioperative acute kidney injury with RIPC, especially the occurrence of moderate and severe acute kidney injury. Furthermore, RIPC was associated with a reduced use of renal replacement therapy and a shorter length of intensive care unit stay. While these results are encouraging, they need to be validated in larger prospective studies, and the potential risks and adverse effects of RIPC must be considered carefully. The effects of repeated limb ischemia with RIPC are not fully known, and clinicians should be mindful of potential harms before widespread use.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention

Keywords: Acute Kidney Injury, Anesthesia, Biological Markers, Blood Pressure, Cardiac Surgical Procedures, Intensive Care Units, Intention to Treat Analysis, Ischemia, Ischemic Preconditioning, Myocardial Infarction, Numbers Needed To Treat, Renal Replacement Therapy, Stroke, Tissue Inhibitor of Metalloproteinase-2


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